What am I

I am so expensive
I am very hard to grow
I am grown in Madagascar
that is faraway I know
I am used in sweet and savoury
I am pure, spicy, delicate too
with a peculiar bouquet
Have I given enough clues?.
What am I?
My first is a commercial vehicle of the white kind
My second says that i am sick
My third is a portion of the French expression, OOH la la
My fourth is the name for the water found at the beach
My fifth is the 4th letter of the alphabet
The answer is
Vanilla Seed

Seren, in the first two lines I thought it was abt me,(my mom pokes me so..) --(in lines 5&6 again, I can hear my hubby's words) ;) a different concept and a great write ... enjoyed reading...
smile and hugs,Mehnaz